The present invention relates to railroad track maintenance equipment and more particularly to a vehicle for performing maintenance on the bed of a railroad track.
It is important for railroad track to remain substantially level and uniform along its length. Although slight and gradual variations in the profile of the track are typically acceptable, rapid or severe longitudinal or lateral variations can have a significant impact on the performance of the track. As a result, significant efforts are made to maintain the railroad track with a level profile. To this end, railroad track is typically laid on a bed of ballast stones, which provide a firm foundation for the ties or sleepers. Once the track is leveled, the ballast stone bed helps to preserve the level of the track for a relatively long period of time. Nonetheless, over extended use the stones shift, crumble or otherwise degrade causing undesired variations in the track, such as bows, twists and undulations. For example, stone under one end of a particular tie may shift or crumble under repeated train passes causing that end of the tie to settle. As the tie settles, it creates a low spot in the rail, making travel over the rail rough and, depending on the severity, possibly increasing the likelihood of a derailment.
To maintain the level of a railroad track, it is necessary to perform periodic maintenance on the railroad track bed. One particularly effective method for maintaining a railroad track bed is to supply new ballast stones to the bed beneath settled ties. Typically, the new ballast stones are blown under the tie using compressed air. As a result, this method is commonly referred to as xe2x80x9cstoneblowing.xe2x80x9d Stoneblowers have been in use for years and provide significant advantages over other maintenance techniques. For example, experience has revealed that track that is maintained by stoneblowing may retain a level profile significantly longer than track maintained using conventional xe2x80x9ctampingxe2x80x9d methods.
Stoneblowing is typically performed by a track maintenance vehicle, called a stoneblower. A stoneblower typically includes a jack for lifting the railroad track and associated ties and at least one workhead for delivering new stone under the lifted ties. A stoneblower workhead typically includes a pair of blowing tubes that can be thrust into the ballast adjacent to the tie to deliver new stone. The blowing tubes are positioned on the workhead to straddle the rail and supply stone on opposites sides of the rail. In use, the blowing tubes are typically aligned with the edge of the tie and include openings toward their lower ends to allow ballast to blown directly beneath the tie. A conventional workhead is mounted toward the bottom of the vehicle on a pair of movable carriages. The carriages permit a limited range of lateral and longitudinal movement of the workhead. Conventional stoneblowers are not well-suited for use in maintaining switches and other complex track configurations. The double carriage arrangement of a conventional workhead often fails to provide enough adjustment to accommodate the complex tie and rail arrangements found in switches and the like. Also, the dual blowing tube workhead is not well-suited for treating many locations in a switch as one blowing tube may impede insertion of the other into narrow locations.
The aforementioned problems are overcome by the present invention wherein a stoneblower is provided with a vertically extended workhead that pivots from a point located near the top of the stoneblower. The position of the workhead is controlled by a pair of hydraulic cylinders operatively connected to a central portion of the workhead. In a preferred embodiment, the workhead includes a single blowing tube extending downwardly from the bottom of the workhead.
In a more preferred embodiment, the stoneblower includes a computerized control system for controlling the position of the workheads. The control system includes an automated height control system that automatically positions the blowing tube at the desired height regardless of the left/right (or lateral) position of the workhead. The uniform height control system automatically adjusts the position of the vertical cylinder to compensate for changes in the height of the blowing tube that would otherwise result from arcuate movement of the workhead.
In an even more preferred embodiment, the workhead includes two pair of workheads, a first pair located over the left rail and a second pair located over the right rail. Each pair of workheads includes a forward workhead having a rearwardly opening blowing tube and a rear workhead having a forwardly opening blowing tube. The forward and rear workheads are adapted to align with the forward and rearward faces of a tie, respectively.
The present invention provides an effective stoneblower that is particularly well suited for maintaining switches and other complex track configurations. The workheads are easily adjustable to treat even narrow locations in the rail. Because the workhead pivots near the top of the vehicle, increased fore/aft and left/right movement is possible with only a relatively small amount of vertical movement. The pivotal mounting permits a broad range of movement of the workhead without requiring a correspondingly broad range of movement in the actuating assembly. In fact, the workhead can even treat locations outside of the lateral profile of the vehicle. Further, the automated height control system permits left and right adjustment of the workhead without requiring manual adjustment of the height of the workhead.
These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.